A punching machine punches a sheet into a predetermined shape by means of a Thomson blade, a die cut roller or the like, thereby forming a product from the sheet. The sheet punched by the punching machine includes a scrap as well as the product. In order to obtain the product from the sheet, therefore, it is necessary to separate the punched sheet into the product and the scrap and remove the scrap away.
In a conventional punching process of sheets, sheets are punched in such a manner that some joints are left between a product and a scrap. A certain number of the punched sheets are stacked, and the products and the scraps are simultaneously separated from each other in the stack. When such an operation is performed by a worker, not only the serious burden is imposed on the workers because large force is required, but also the working efficiency is low. On the other hand, when such an operation is performed by a machine, the working efficiency is high but a size of the machine becomes large and the machine becomes complicated.
In addition, there is provided a punching machine including a separating mechanism for separating each of punched sheets into a product and a scrap while sequentially conveying the sheets one by one (see for example JP-A-2000-127097). The punching machine described in JP-A-2000-127097 blows air jet onto the punched sheet without joints between the product and the scrap so as to separate the product and the scrap and remove the scrap away while conveying the sheet along a conveying path.
Although the punching machine can reliably separate the product and the scrap in the case that the scrap is small or has a simple shape, it cannot separate the product and the scrap with the air jet completely in case that the scrap is large or has a complicated shape.